Apparatus for continuously forming vacuum packaged body

ABSTRACT

An apparatus for vacuum packaging a continuous packaged body of the invention is so constructed that a seal bar  35  and a seal table  36  are mounted in the respective skirt parts  39, 40  of seal blocks  22, 23  opposite to each other with a tube film  20  interposed between them, and in the case of nipping the tube film  20  by both seal blocks  22, 23  plural intermittent teeth  44. 45  spot close the tube film on the inner sides of both skirt parts as one points in the transfer direction of a material to be packaged. Simultaneously, in ports  47  of the face of a standing gap  46  formed thin along the outsides of the above intermittent teeth, the tube film is flared by vacuum suction force, and from the section of the tube film cut by forcing a cutting edge  51  in the seal bar into a receiving groove  52  cut in the seal table, the air in the tube film is sucked through the spot closing gap and the receiving groove  52.  By spot closing the tube film by the above intermittent teeth  44, 45,  distortion of the film in displacement and suction of the air is restrained, and then the cut end of the tube film is heat sealed by the seal bar  35  and the seal table  36.

FIELD OF THE INVENTION

[0001] This invention relates to an apparatus for sequentially isolating and sealing a tube film storing a number of materials to be packaged at equal spaces in a column and moving between the respective materials to be packaged and simultaneously evacuating the interior of the tube film to continuously form a vacuum packaged body.

BACKGROUND OF THE INVENTION

[0002] U.S. Pat. No. 4,601,159 discloses the technology where a longitudinally moving tube film is perpendicularly nipped by a pair of seal bars, and immediately before the respective materials to be packaged in the tube film are isolated and sealed, the tube film is cut by cutting edges incorporated in the seal bars, and the air in the tube film is removed through the cut portion to form a continuous vacuum packaged body.

[0003] The details of the technology disclosed in the '159 patent specification are such that the tube film is cut between the front and rear materials to be packaged, the cut end parts are sucked to adhere to a dome-like wall inner surface and largely opened, and the air in the tube film is removed from the opened parts. The positive opening of the cut end parts is intended for heightening the efficiency of removing the air in the tube film, but unsuppressed opening of the tube film in the apparatus creates a high possibility of causing distortion at the open end parts, so that even if the open edge is later sealed by heat, the mentioned distortion impairs air tightness of the sealed part and exerts a bad influence upon the sealing performance of the vacuum packaged body. Consequently, the '159 patent apparatus while being adapted to cut a film opening part and remove the same, and heat-seal two new opposite cut ends of both sides of the removed part, the apparatus has the disadvantage of causing lowering of efficiency due to the waste of film during cutting and removing of the film and the complicatedness of the operation process.

SUMMARY OF THE INVENTION

[0004] It is an object of the invention to heighten the packaging efficiency by restraining distortion of a film cut part due to air vibration and performing high airtight sealing without distortion of the cut part so as to prevent wasteful removal of film due to distortion during cutting of tube film, and removing of the air in the tube film by suction action on the cut part.

[0005] The object of the invention is further achieved by providing a packaging apparatus including a seal bar and a seal table for sealing a tube film in the direction right angled to the direction of a track along which the tube film storing materials to be packaged at equal spaces in a column is transferred along the longitudinal direction, the apparatus disposed midway of the track being formed by:

[0006] 1. a pair of seal blocks supporting the seal bar and the seal table outside the opposite surfaces of the seal bar and the seal table by the skirt parts thereof and supporting the same;

[0007] 2. means for spot closing the tube film by plural intermittent teeth at the inner sides of the skirt parts as one points in the transfer direction of materials to be packaged while the respective skirt part edges of both seal blocks nip the tube film corresponding to the pitch transfer of the materials to be packaged;

[0008] 3. a sub-vacuum line for applying vacuum suction force to each part formed on the faces of a standing gap to flare the thin tube film at the standing gap formed along the outside of the intermittent teeth;

[0009] 4. a main vacuum line for pushing a cutting edge slidably disposed in the middle of the interior of the seal bar into a receiving groove cut in the seal table to cut the tube film in the area surrounded by the skirt parts and sucking the air in the bag in front of the seal blocks through the spot nipping gap from between the seal bars and the seal table through the receiving groove in the seal table; and

[0010] 5. means for welding the cut sides of the tube film by relative approach of the seal bar and the seal table after the above removal of air.

[0011] According to the invention, every time the respective materials to be packaged are moved by one pitch, the tube film for covering the materials to be packaged is nipped by the skirt part edges of the paired seal blocks. In this case, the plural intermittent teeth formed on the front side of the skirt parts, as one points in the transfer direction of the material to be packaged, spot close the tube film, and the vacuum suction force of a sub-vacuum line is applied to each port formed on the standing gap along the front side of the intermittent teeth to flare the tube film, so that the tube film forms a nipping gap between the respective intermittent teeth. The cutting edge provided on the seal bar installed in one seal block is forced into the receiving groove of the seal table in the other seal block to cut the tube film in the area surrounded by the skirt parts, and the air in the bag in front of the seal blocks is sucked through the spot closing gap from between the seal bar and the seal table into the main suction line through the receiving groove in the seal table.

[0012] The tube film is thus flared by the sub-vacuum suction force to stick the tube film to the faces of the thin standing gap, and the air in the tube film is removed through the spot gap between the respective intermittent teeth, whereby the vibration of the tube film due to the removed air impact is restrained to prevent the film from being distorted, and the above inhibition of distortion eliminates cut-down of the film so as to prevent waste of the film.

[0013] In one preferred embodiment of the invention, the sub-vacuum line and the main vacuum line are connected to a vacuum pump through a vacuum tank. The intermittent removal of air in the tube film corresponding to the pitch transfer of the material to be packaged is performed impulsively by pressure accumulation function of the vacuum tank so that the capability is not lowered.

[0014] In another preferred embodiment of the invention, cooling water is passed through the intermittent teeth formed by the skirt parts of the seal blocks to be cooled. In the case of spot nipping the film by the thus constructed intermittent teeth, there is possibility that dot-like cheloid is generated in the film by heat of the tips of the intermittent teeth conducted from the seal bar to spoil the beauty of sealing and sealing strength. Such a problem is solved by the above cooling.

[0015] In still another embodiment of the invention, simultaneously with nipping the tube film by both seal blocks, the material to be packaged in front of the seal blocks is pressed and supported by a block made of urethane foam. Shrinkage of the tube film occurs due to removal of air through the spot gaps between the respective intermittent teeth. To compensate for such shrinking, the material being packaged is softly pressed and supported by a block made of urethane foam which inhibits shrinkage of the film and restrains the generation of creases of the film resulting in beautiful sealing. Thus, sealing strength can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a schematic side view of an apparatus according to the invention.

[0017]FIG. 2 is a partial front view of a frame supporting a seal block.

[0018]FIG. 3 is a sectional view of a pair of movable seal blocks.

[0019]FIG. 4 is a front view of the central parts of the faces of the seal blocks.

[0020]FIG. 5 is a perspective sectional view of the lower seal block.

[0021]FIG. 6 is a diagram for explaining in an enlarged diagram the packaged body nip part of a pair of seal blocks.

[0022]FIG. 7 is a plan view showing the sealed part of the packaged body.

[0023]FIG. 8 is a side view of a tube film transport track.

PREFERRED EMBODIMENTS

[0024] A tube film 20 in FIG. 1 is formed by rolling a belt-like film in a bag form-fill-sealing machine, and simultaneously a number of materials 21 to be packaged are stored at equal spaces in the interior thereof. While a pair of upper and lower seal blocks 22, 23 installed in the same packaging machine respectively displace along a dotted-line track 24 during transfer of the materials 21 being packaged in the direction of the arrow 15 (FIG. 1). Seal blocks 22, 23 nip the tube film 20 between the materials 21 being packaged and perform both air suction and heat sealing action on the film. The construction of the invention apparatus according to a first embodiment will next be described.

[0025]FIG. 2 shows in a partial front view the left half of a frame structure supporting the above paired seal blocks 22, 23. It should be understood that the right half of the frame structure, not illustrated, is a symmetrical continuation of the structure illustrated in FIG. 2. That is, the frame structure being described is so constructed that the upper and lower ends of a pair of vertical side plates 25 on both sides of the structure are connected by upper and lower tie members 26 to form a portal frame. Slide blocks 27 respectively fixed to the lower ends of the side plates 25 on both sides of the frame structure are slidably supported on a pair of horizontal guide rods 28, and both ends of the upper and lower seal blocks 22, 23 are slidably supported on round post members 29 respectively erected on slide blocks 27. The previously mentioned portal frame incorporating the side plates 25 and tie members 26 is reciprocated along the guide rods 28 by a crank mechanism not shown.

[0026] Rotation power is transmitted from an outside power source (not shown) to a pinion 31 mounted on a main shaft 30 rotatably installed on the portal frame. Vertical motion of the upper seal block 22 along the round post members 29 is achieved through a crank lever 32 and a connecting rod 33 fixed to the end of the main shaft 30 while vertical motion of the lower seal block 23 along the round post members 29 is achieved by the eccentric motion of the lower end of a rod 34 x which engages an eccentric cam 34 at the end of the main shaft 30. Accordingly, both movable seal blocks 22, 23 repeatedly execute both longitudinal and vertical movement along the dotted line track 24 of FIG. 1.

[0027]FIG. 3 in a section view shows the condition where the leading end of the trailing package stored in tube film 20 between representative front and rear materials 21 is nipped by the upper and lower seal blocks 22, 23. As further seen in FIG. 3, the upper seal block 22 is provided with a seal bar 35 mounted in a skirt part 39 formed as a continuation of the lower side of seal block 22. FIG. 3 also illustrates the lower seal block being provided with a seal table 36 mounted in a reverse skirt part 40 formed as a continuation of the upper side of the seal block 23. The seal bar 35 and the seal table 36 are also each illustrated as respectively containing a pipe heater 37 for generating film welding heat.

[0028] The front sides 39 a, 40 a (FIG. 3) of the respective skirt parts of the seal blocks 22, 23 in the transfer direction 38 of the material 21 being packaged form a standing gap ranging from 1 mm to 2 mm between the opposite edges and through which the air 41 in the front tube film 20 can be circulated. An embodiment of forming means for such a gap is mentioned later.

[0029]FIG. 4 shows the front faces of the central parts of both seal blocks 22, 23, and FIG. 5 shows the perspective section of the lower seal block 23. A pair of attached upper and lower blocks 42,43 embedded in the respective seal blocks 22, 23 and fixed opposite to each other have plural intermittent teeth 44, 45 which when the seal blocks are closed are fastened upon the tube film at the inner edges. Plural continuous standing gaps 46 are formed between the outer edges of the intermittent teeth and plural ports 47 (FIG. 5) formed on the upper and lower sides of the standing gaps are connected to a sub-vacuum line 49 through passages 48 as seen in FIGS. 3, 5 and 6.

[0030] It is apparent from FIG. 6 of an enlarged scale that by vacuum suction of the upper and lower passages 48, the tube film 20 is sucked to the upper and lower surfaces of each standing gap 46 ranging from 1 mm to 2 mm and forced open. In this case, the upper and lower intermittent teeth 44, 45 close the tube film 20 at corresponding intermittent locations to limit random expansion, thereby preventing occurrence of distortion in the tube film. In this case, cooling water flowing through a drain passage 69 penetrating the attached blocks in the lateral direction prevents heat transfer from the seal bar or the seal table to the intermittent teeth.

[0031] In FIG. 2, a first fluid cylinder 50 fixed to the upper seal block 22 vertically slides a cutting edge 51 mounted in the seal bar 35 and forces the cutting edge 51 into a receiving groove 52 of the seal table 36 in the lower area, thereby cutting the tube film. Such a condition is known from FIG. 3 in which when the cutting edge 51 is forced into the lower receiving groove 52 to cut the tube film, the air in the tube film 20 at the front is drawn out into the main vacuum line 53 through the above receiving groove 52.

[0032] As shown in FIG. 1, the described sub-vacuum line 49 is connected to a vacuum tank 61 of designated capacity connected to a vacuum pump 60 through a normally-closed first opening and closing valve 62, and the described main vacuum line 63 is connected to the vacuum tank 61 through a normally-closed second opening and closing valve 64. The upper and lower movable blocks 22, 23 completely nip the tube film 20, and simultaneously when the vacuum pressure is applied to the sub-vacuum line 49 by opening the first opening and closing valve 62, the tube film is sucked to the upper and lower surfaces of the standing gap 46 in FIG. 4. In this case, a packing 65 mounted on the upper surface of the seal block 23 in FIG. 5 surrounds the receiving groove 52 formed in the seal table as shown in FIG. 7, and the air in the tube film opened by cutting operation of the cutting edge 51 is passed between the respective spot nipping parts 44, 45 and drawn out toward the tank 61 simultaneously with opening of the second opening and closing valve 64 in FIG. 1. The suction in this case is impulsively performed by the capacity action of the vacuum tank 61 (FIG. 1), and subsequently, the seal bar 35 moved downward by a second fluid cylinder 66 in FIG. 2 is pressed to the seal table 36 to seal the opening part of the tube film.

[0033] As shown in FIG. 8, the upper seal block 22 is provided with soft pressing blocks 71, 72 made of urethane foam and fixed to the front and rear thereof. The tube film 20 is nipped by the relative approach of both upper and lower seal blocks 22, 23 and when the air in the tube film 20 is sucked, the pressing blocks 71, 72 press the material 21 being packaged to the lower belt conveyers 73, 74, thereby substantially inhibiting the shrinkage of the tube film caused by the described vacuum suction. 

What is claimed is:
 1. A packaging apparatus, comprising a seal bar and a seal table disposed in the midway of a track for transferring a tube film storing materials to be packaged at equal spaces in a column along the longitudinal direction for sealing said tube film in the direction right-angled to the track direction, wherein said packaging apparatus comprises: (a) a pair of seal blocks surrounding said seal bar and seal table outside the opposite surfaces of said seal bar and seal table respectively by the skirt parts thereof and supporting the same; (b) means for spot closing said tube film by plural intermittent teeth on the inner sides of said skirt parts as one points in the transfer direction of materials to be packaged while the respective skirt part edges of both of said seal blocks nip said tube film corresponding to the pitch transfer of said materials to be packaged; (c) a sub-vacuum line for applying vacuum suction force to each port formed on a standing gap to flare said tube film at said standing gap formed thin along the outsides of said intermittent teeth; (d) a main vacuum line for forcing a cutting edge stably disposed in the middle of the interior of said seal bar into a receiving groove cut in said seal table to cut said tube film in an area surrounded by said skirt parts, and sucking the air in a bag in front of said seal blocks through said spot closing gap from said seal bar and said seal table through said receiving groove in said seal table; and (e) means for welding the cut sides of said tube film by the relative approach of said seal bar and said seal table after said removal of air.
 2. The apparatus according to claim 1, wherein corresponding to the operation of nipping said tube film between two front and rear materials to be packaged in said tube film by a pair of movable blocks, first a first opening and closing valve mounted between said sub-vacuum line and a vacuum pump is opened, and then a second opening and closing valve mounted between said main vacuum line and said vacuum pump is opened.
 3. The apparatus according to claim 2, wherein said sub-vacuum line and said main vacuum line are connected to said vacuum pump through a vacuum tank.
 4. The apparatus according to claim 1, wherein intermittent teeth formed by said skirt parts of said seal blocks are provided with cooling means for inhibiting transfer of heating heat of said seal bar mounted in the interior of said skirt part.
 5. The apparatus according to claim 1, wherein simultaneously with nipping said tube film by both of said seal blocks, a material to be packaged in front of said seal blocks is pushed and supported by blocks made of urethane foam.
 6. A packaging apparatus for sealing a tube film that surrounds a plurality of spaced packages moving in a transfer direction, said seal being perpendicular to said transfer direction, said packaging apparatus comprising: (a) an upper seal block and a lower seal block positioned above and below the plurality of packages, at least one of the seal blocks being moveable between an open and a closed position, each of said seal blocks having a slot formed therein and a skirt portion surrounding the slot, wherein the skirt portion has an input side and an output side, each being formed such that when the upper and lower seal blocks are in the closed position, a substantially continuous seal line is formed across the tube film at the input side, and a gap is formed along the output side; (b) a plurality of intermittently spaced nipping teeth formed along the output side of the skirt portion to nip the tube film at the output side, said nipping teeth being positioned so as to form one or more ports between the upper and lower sealing blocks along the gap when the upper and lower seal blocks are in the closed position; (c) a sub-vacuum line through which a vacuum suction force to each port is produced to maintain the tube film open within each of the ports when the upper and lower seal blocks are in the closed position; (d) a main vacuum line through which a substantial vacuum is produced within the package positioned adjacent to the output side when the upper and lower seal blocks are in the closed position; (e) a seal bar positioned with the slot formed in one of either the upper or lower seal blocks, and a seal table positioned within the slot formed in the other seal block, wherein at least one of said seal bar or seal table is moveable to a sealing position to seal the tube film there between; (f) a sealing element to form a first seal along a trailing edge of a package positioned at the output side and a second seal along a leading edge of a package positioned at the input side, said seals being made after the substantial vacuum is produced in the package positioned adjacent to the output side; and (g) a cutting tool to transversely cut the tube film after the seals are formed.
 7. The apparatus according to claim 6, further comprising a sub-vacuum valve positioned between the sub-vacuum line and a vacuum pump, and a main vacuum valve positioned between the main vacuum line and the vacuum pump, wherein the sub-vacuum valve is opened to draw the vacuum suction force to each port before the main vacuum valve is opened to draw the substantial vacuum in the package.
 8. The apparatus according to claim 7, wherein said sub-vacuum line and said main vacuum line are connected to said vacuum pump through a vacuum tank.
 9. The apparatus according to claim 6, further comprising cooling means positioned near the intermittent teeth at the output side of the upper and lower sealing blocks for inhibiting heat transfer of said seal bar in the slot of the seal block.
 10. The apparatus according to claim 6, further comprising at least one push block positioned so that simultaneously with the tube film being nipped by the intermittent teeth on both of said seal blocks, a material to be packaged in front of said seal blocks is pushed and supported by the at least one push block.
 11. The apparatus according to claim 10, wherein the at least one push block comprises a urethane foam.
 12. The apparatus according to claim 6, wherein the intermittent teeth are formed on attachment blocks that are mounted on the output side of the skirt portion of each of the upper and lower seal blocks.
 13. The apparatus according to claim 6, wherein the sub-vacuum line comprises a plurality of passages that communicate between the sub-vacuum line and spaces formed between adjacent intermittent teeth.
 14. The apparatus according to claim 12, wherein the sub-vacuum line comprises a plurality of passages formed in the attachment blocks that communicate between the sub-vacuum line formed in the upper and lower seal blocks and spaces formed between adjacent intermittent teeth.
 15. A method of evacuating a section of a linear tube formed of two layers of film containing material which is stored in spaced apart sections extending along the length of the tube, comprising: (a) clamping the layers of film between sets of intermittent teeth positioned transverse and at the end of a section of the tube; (b) applying a first vacuum to the outer surface of those parts of both layers of film located between said teeth so as to cause such parts outer surfaces to form passages communicating with the interior of the section of said tube adjoining and extending outwardly from said teeth; (c) applying a second vacuum to said passages so as to exhaust air from said adjoining section of said tube; and (d) sealing said one end of said adjoining section following exhausting of said air. 